Electron discharge device



May 30, 1939. TEAL 2,160,799

ELECTRON DISCHARGE DEVICE Filed Aug. 51, 1937 'i g l afi'l u lglllu ii 1mm n II II II T0 OUTPUT CIRCUIT INVENTOR G. K. TEAL ATTORNEY Patented May 30, 1939 UNITED STATES PATENT OFFICE" 2,160,799 ELECTRON DISCHARGE DEVICE Application August 31,

20 Claims.

This invention relates to electron discharge devices and more particularly to such devices having a plurality of secondary electron emitting electrodes and commonly known as electron multipliers.

'One object of this invention is to expedite the manifold amplification of relatively weak electrical signals.

Another object of this invention is to simplify the construction of electron discharge devices having a multiplicity of electrodes and thereby to facilitate thefabrication of such devices.

A further object of this invention is to improve the efficiency and operating characteristics of electron multipliers.

In one illustrative embodiment of this invention, an electron multiplier comprises a primary cathode, which may be of the photoelectric type, a collector electrode or anode remote from the primary cathode, and a plurality of successively arranged auxiliary electrodes or secondary cathodes between the cathode and the collector electrode and adapted to emit secondary electrons.

In accordance with one feature of this invention, the auxiliary electrodes or secondary cath-.

and in helical formation, the first of the secondary cathodes being in proximity to the primary cathode and the last in the series of secondary cathodes being in cooperative relation with the collector electrode or anode, r

In accordance with another feature of this invention, a second series of auxiliaryelectrodes is provided, these-electrodes also being arranged in helical formation and in juxtaposition to the secondary-cathodes. These auxiliary electrodes may be utilized during the operation of the device to provide electrostatic fields assisting in the determination of the trajectories followed by the electrons emanating from the primary and secondary cathodes.

In accordance with still another feature of this invention, means are provided for concentrating the electron streams emanating from the various cathodes and confining the streams to desired paths. In one form such means may comprise a plurality of plate members arranged in pairs at opposite extremities of the cathodes and defining enclosures with the cathodes and the auxiliary or field electrodes.

The invention and the foregoing and other features thereof will be understood more clearly and fully from the following detailed description with reference to the accompanying drawing in which:

Fig. 1 is an elevational, view in perspective of odes are arcuate members mounted edge to edge 1937, Serial No. 161,747

an electron discharge device illustrative of one embodiment of this invention;

v Fig. 2 is a fragmentary View showing particularly the form and relation of one series of auxiliary electrodes and the association of theleading-in conductors therewith; 4

, Fig. 3 is a view in cross-section along line 33 of Fig. 1; and

Fig. 4- is a diagrammatic view showing one illustrative electrical association of the electrodes in the device shown in Fig. 1.

Referring now to the drawing, the electron discharge device illustrated therein comprises an evacuated enclosing vessel having vitreous, inner and outer cylindrical walls I0 and I I respectively, which preferably are coaxial and substantially coextensive. Mountedupon the inner surface of the outer wall II are a primary cathode I2 and a plurality of arcuateQgeneraHy rectangular, auxiliary electrodes or secondary cathodes l3 arranged side by side in helical formation and uniformly spaced. Eachof the cathodes I2 and I3 may comprise a metallic base or film deposited upon the inner surface of the wall I I and homogeneously adhering thereto, the inner surface of each base or film being coated/or sensitized so that the inner surface of the primary cathode I2 isphotoelectrically active and the inner surface of each of the secondary cathodes I3 has good secondary electron emitting properties. For example, the bases or films may be of silver and treated with oxygen and caesium to form on the inner surface thereof a matrix or coating includ-- 7 ing silver, caesium oxide, and some free caesium. Electrical connection to the primary cathode I2 may be established through a leading-in conductor I4 sealed in the wall II and contacting with the base or film comprising this cathode. Similarly, electrical connection to the secondary cathodes I3 may beestablished through conductors I5 sealed in the wall- II and contacting with the secondary cathode bases or films.- I Mounted upon the inner cylindrical wall II) are a series of arcuate, generally'rectangular, auxiliary electrodes I6 equal in number to the primary and secondary cathodes'and arranged in helical formation. The auxiliary electrodes I6 are spaced in the same relation as the cathodes I2 and I3 so that the first auxiliary electrode I6 is in radial alignment with the primary cathode I2 and each of the other electrodes I6 is in radial alignment with the corresponding one of the secondary cathodes I3. The various electrodes I6 may be constituted by metal films, for example, films of silver, deposited upon the wall III. If

Ill

desired, these films may be sensitized similarly to the films of the secondary cathodes l3 so that they have good secondary electron emitting characteristics. Electrical connection to the auxiliary electrodes It may be established through leading-in conductors l1 sealed in the wall In and contacting with the films I6. The conductors ll extend from the ends of the wall Ill and all but the end portions thereof preferably are encased in insulating sleeves l8. 7

Disposed above each of the corresponding cathodes l2 and I3 and electrodes [6 and coextensive therewith is an arcuate metallic nonmagnetic plate l9, supported by a rigid leading-in conductor 20 sealed in and extending from the outer wall H, the several plates l9' beingsub stantially parallel to and slightly above the upper edges of the corresponding electrodes. A series of other metallic, non-magnetic plates 2|, supported by leading-in conductors 22 sealed in and extending from the outer wall H, are positioned parallel to the lower edges of the corresponding cathodes l2, l3 and electrodes IS. The plates 2! are substantially coextensive with the oathodes I2, l3 and electrodes l6 and are substantially parallel to the corresponding plate l9. Preferably, as indicated in Fig. 3, each of the plates [9 and 2! extends to immediately adjacent or contacts with the walls Ill and H so that the plates together with the cathodesand electrodes l6 define a series of axially aligned enclosures or canals of rectangular section. 7

An anode or collector electrode 23, which may be a rectangular metallic plate, is mounted adjacent and parallel to one end of the enclosure,

or canal defined by the lowermost plates l9 and 2! and electrodes l3 and I6, and is supported by a rigid leading-in conductor 24 sealed in and extending from the wall H.

Extending through the opening defined by the inner wall [0 is a cylindrical bar magnet 25, which is strongly magnetized and produces a strong magnetic field between the inner surfaces of the cathodes l2 and I3 and the auxiliary electrodes l6 and parallel to the longitudinal axis of the enclosing vessel. Preferably the magnet 25 extends an appreciable distance beyondthe ends of the enclosing vessel so that a field of substantially uniform intensity is produced throughout the length of the enclosing vessel.

During operation of the device, as indicated in Fig. 4 wherein by way of illustration but five of the sets of electrodes 16 and 12 or I3 are shown, the successive secondary cathodes l3 are operated at uniformly increasing positive potentials with respect to the primary cathode I2, For example, each secondary cathode may be maintained of the order of 50 volts positive with respect to the next preceding cathode. The necessary potentials may be obtained from a potentiometer device 26 connected across a suitable source such as a rectifier 21. Each of the auxiliary electrodes It may be connected to the next succeeding cathode so that it is at a positive potential with respect to the cathode in juxtaposition thereto. Corresponding plates l9 and 2! may be maintained at a potential, for example of the order of 5 volts, positive with respect to the cathode corresponding thereto. The collector electrode or anode 23 is maintained positive, for example of the order of volts, with respect to the last of the secondary cathodes 13 through a source, such as a battery 28, in circuit therewith as shown in Fig. 4.

The primary cathode I2 may be energized to cause the emission of electrons therefrom, by a beam of light emanating from a suitable light source 29 and focussed upon the primary cathode. Under the infiuence of the magnetic field produced by the magnet 25 and the potentials upon the auxiliary electrode 16 in juxtaposition thereto and the next succeeding secondary cathode l3, the electrons emanating from the cathode l2 will traverse paths such as indicated by the dotted line A in Fig. 3 and flow to and impinge upon the next succeeding cathode. The corresponding plates I9 and 2| serve to focus the electrons and confine them to paths along the center of the enclosures or .canals formed by the associated electrodes.

The electrons impinging upon the secondary cathode l3 nearest the primary cathode cause the emission of secondary electrons from this secondary-cathode and these electrons are attracted and guided to, and impinge upon the next secondary cathode l3, the secondary electrons traversing paths as indicated approximately by the dotted line B in Fig. 3. The secondary electrons thus liberated flow to and impinge upon the next secondary cathode to cause the emission of other secondary electrons therefrom. Inasmuch as the secondary cathodes are sensitized as described heretofore, the electron current emanating from each of the secondary cathodes is greater than the primary or secondary current flowing thereto. Consequently, in effect, an electron multiplication and an amplification of the original current occurs at each of the secondary cathodes.

The secondary electrons emanating from the last of the secondary cathodes l3 flow to the anode or collector electrode 23 and constitute the output current of the device. The magnitude of this current will be dependent upon the intensity ofthe light beam focussed upon the primary electrode l2 and will vary in accordance with variations in the intensity of the light beam.

As pointed out heretofore, the auxiliary electrodes I6 may be of such construction as to have good secondary electron emitting characteristics. If desired, these electrodes may be utilized as the cathodes in which case the polarity of the magnet 25 should be'opposite to that shown in Fig. l and the connections illustrated in Fig. 4 should be changed so that the electrodes I6 are at successively increasing positive potentials and the electrodes l2 and 13 have the relative potentials indicated for the electrodes [6 in Fig. 4.

Although a specific embodiment of the invention has been shown and described, it will be understood, of course, that various modifications may be made therein without departing from the scope and spirit of this invention as defined in the appended claims.

What is claimed is:

1. An electron discharge device comprising a primary cathode, a collector electrode spaced from said cathode, and a plurality of electrically separate, substantially rectangular secondary electrodes mounted side by side and in helical formation between said primary cathode and saidcollector electrode, said secondary electrodes having corresponding surfaces thereof adapted to emit secondary electrons.

2. An electron discharge device comprising a plurality of arcuate cathodes mounted in helical formation in a cylindrical boundary, a collector electrode, and a plurality of auxiliary electrodes mounted in helical formation in a cylindrical boundary coaxial with said first boundary.

3. An electron discharge device comprising a primary cathode, a-collectorelectrode, a plurality of secondary" electron emitting cathodes in-cooperative relation withsaid primary cathode'and said collector electrode, each secondary cathode being a segment of a cylinder and said secondary cathodesb'eing mounted end-'to-end in spaced relation inhelic'al formation in a cylindrical boundary, and means for focussing the electrons emanating from said primary and secondary cathodes. l

4. An electron discharge device comprising a primary cathode, a collector electrode, a plurality of secondary cathodes between said primary cathode and said collector electrode, said secondary cathodes being mounted in helical formation and in a substantially cylindrical boundary, and a plurality of auxiliary electrodes each in juxtaposition to one of said secondary cathodes.

5. An electron discharge device comprising a primary cathode, a collector electrode, a plurality of arcuate secondary cathodes between said primary cathode and said collector electrode, said secondary cathodes being mounted edge to edge in helical formation and in a substantially cylindrical boundary, and a plurality of arcuate auxiliary electrodes, one opposite each of said secondary cathodes and in radial alignment therewith, said auxiliary electrodes lying in a boundary substantially coaxial with said cylindrical boundary.

6. An electron discharge device comprising a primary cathode, a collector electrode, a plurality of electrically separate secondary cathodes between said primary cathode and said collector electrode, mounted in helical formation in a substantially cylindrical boundary, means for producing a magnetic field adjacent said primary and secondary cathodes, and means for producing electrostatic fields adjacent said primary and secondary cathodes.

'7. An electron discharge device comprising a primary cathode, a collector electrode, a plurality of arcuate electrodes between said primary cathode and said collector electrode, mounted in helical formation and in a substantially cylindrical boundary, corresponding surfaces of said arcuate electrodes being adapted to emit secondary electrons, means for producing a magnetic field adjacent and parallel tosaid surfaces, and means including a plurality of electrodes opposite said surfaces for producing electrostatic fields in the vicinity of said surfaces.

8. An electron discharge device comprising a primary cathode, a collector electrode, a plurality of aligned secondary cathodes between said primary cathode and said collector electrode, and a plurality of plate electrodes adjacent opposite sides of said secondary cathodes, at substantially right angles to the surfaces of said secondary cathodes and electrically separate therefrom.

9. An electron discharge device comprising a primary cathode, a collector electrode, a series of arcuate, substantially rectangular secondary cathodes mounted in helical formation and in a substantially cylindrical boundary, and a plurality of pairs of conductive plates, the plates of each pair being mounted adjacent opposite sides of a corresponding one of said secondary cathodes.

10. An electron discharge device comprising two opposed series of electrodes mounted in helical formation in substantially coaxial cylindrical boundaries, the electrodes in one of said series having corresponding surfaces coated with an electron emitting material, a collector electrode, and means for confining electrons emanating from said surfaces to paths between said two series of electrodes.

11. An electron discharge device comprising a plurality of successively arranged cathodes, a collector electrode, and metallic means adjacent said cathodes, electrically separate therefromand defining therewith a series of electrically separate aligned enclosures arranged end to end.-

12. An electron discharge device comprising a plurality of substantially rectangular cathodes mounted successively and edge to edge, a collector electrode, and metallic means adjacent and electrically separate from said cathodes and defining therewith a series of longitudinally aligned substantially tubular enclosures.

13. An electron discharge device comprising a primary cathode, a collector electrode, a. plurality of secondary cathodes mounted in helical formation between said primary cathode and said collector electrode, and a pluralityof metallic members adjacent said secondary cathodes and defining therewith a sectionalized substantially helical enclosure.

14. An electron discharge device comprising two equal series of arcuate electrodes mounted in helical formation and in substantially coaxial boundaries, corresponding electrodes in said series being in radial alignment and the electrodes in one of said series of electrodes having the surfaces thereof toward the electrodes of the other series sensitized to be electron emissive, a collector electrode, and a plurality of pairs of plate members, the plate members of each of said pairs being adjacent opposite sides of corresponding arcuate electrodes and defining aligned canals therewith.

15. An electron discharge device comprising a primary cathode, a collector electrode, a plurality of arcuate substantially rectangular secondary cathodes mounted in helical formation between said primary cathode and said collector electrode, said secondary cathodes having corresponding surfaces thereof adapted to emit secondary electrons, a plurality of auxiliary electrodes each opposite the emitting surface of a corresponding one of said secondary cathodes, and field plates adjacent opposite sides of said surfaces.

16. An electron discharge device comprising a pair of cylindrical insulating members, disposed one within the other, a primary cathode, a collector electrode, a series of secondary cathodes mounted upon one of said insulating members, and a series of auxiliary electrodes mounted upon the other of said members and disposed opposite said secondary cathodes.

17. An electron discharge device comprising a pair of coaxial, substantially cylindrical insulating members disposed one within the other, a primary cathode, a series of electrodes mounted upon the outer wall of the inner of said members, and a series of electrodes mounted upon the inner wall of the outer of said members and opposite said first electrodes, the electrodes of one of said series including a metallic deposit upon the wall mounting said one series.

18. An electron discharge device comprising a pair of coaxial, substantially cylindrical insulating members disposed one within the other, a

' primary cathode, a collector electrode, a plurality of electrodes mounted in helical formation upon a wall of one of said insulating members, each of said electrodes including a metallic film on said wall adapted to emit secondary electrons, and a 20. An electron discharge device comprising an enclosing vessel having inner and outer cylindrical walls, a primary cathode and a collector electrode within said vessel, a series of arcuate secondary cathodes mounted in helical formation upon the inner surface of one of said walls, a series of auxiliary electrodes mounted upon the inner surface of the other of said walls and opposite said secondary cathodes, and a magnet Within said inner wall.

GORDON K. TEAL. 

